[Measurement of local oxygen parameters for detection of cerebral ischemia. The significance of cerebral near-infrared spectroscopy and transconjunctival oxygen partial pressure in carotid surgery]

Comparison of the effect of sevoflurane or propofol anesthesia on the regional cerebral oxygen saturation in patients undergoing carotid endarterectomy: a prospective, randomized controlled study

Background

The monitoring of regional cerebral oxygen saturation (SrO₂) using near-infrared spectroscopy is useful method to detect cerebral ischemia during. Sevoflurane and propofol decrease cerebral metabolic rate (CMRO₂) in a similar manner, but the effects on the cerebral blood flow (CBF) are different. We hypothesized that the effects of sevoflurane and propofol on SrO₂ were different in patients with deficits of CBF. This study compared the effect of sevoflurane and propofol on SrO₂ of patients undergoing cerebral endarterectomy (CEA).

Method

Patients undergoing CEA were randomly assigned to the sevoflurane or propofol group (n = 74). The experiment was preceded in 2 stages based on carotid artery clamping. The first stage was from induction of anaesthesia to immediately before clamping of the carotid artery, and the second stage was until the end of the operation after clamping of the carotid artery. Oxygen saturation (SrO₂, SpO₂), haemodynamic variables (blood pressure, heart rate), respiratory parameters (end-tidal carbon dioxide tension, inspired oxygen tension), concentration of anesthetics, and anesthesia depth (bispectral index score) were recorded.

Results

During stage 1 period (before carotid artery clamping), the mean value of the relative changes in SrO₂ was higher (P = 0.033) and the maximal decrease in SrO₂ was lower in the sevoflurane group compared with the propofol group (P = 0.019) in the contralateral (normal) site. However, there is no difference in ipsilateral site (affected site). SrO₂ decreased after carotid artery clamping and increased after declamping, but the difference was not significant between two groups. Changes in mean arterial blood pressure was lower in sevoflurane group than propofol group after the carotid artery declamping (P = 0.048).

Conclusion

Propofol-remifentanil anesthesia was comparable with sevoflurane-remifentanil anesthesia in an aspect of preserving the SrO₂ in patients undergoing carotid endarterectomy.

Trial registration

Clinical Trials.gov identifier: NCT02609087, retrospectively registered on November 18, 2015.

[Cognitive functions and cerebral oxygenation of older patients after general and regional anaesthesia]

OBJECTIVE

The aim of the present study was to show the influence of cerebral oxygenation (regional cerebral oxygen saturation rSO(2) by near infrared spectroscopy) and of the nocturnal arterial oxygen saturation (SatO(2) by pulse oximetry) on the restitution of cognitive functions in patients aged between 40 and 85 years scheduled for elective hip arthroplasty.

METHODS

A total of 40 patients (ASA II) were randomized to be operated either in general anaesthesia or regional anaesthesia. The patients were additionally classified by age (40-64 years and 65-85 years). Cognitive functions were tested 14-16 h pre-operatively (t0), 1.5 h post-operatively (t1) and at the first and third postoperative days (t2 and t3). During testing, as well as during surgery and postoperatively until t1, rSO(2) was continuously measured. SatO(2) was measured in the night before surgery (N0) and for 3 nights after surgery (N1, N2, N3) between 22.00 p.m. and 5.00 a.m. These measurements were divided into interval groups (80-83%, 84-87%, 88-91%, 92-95%, 96-100%).

RESULTS

Almost all cognitive functions were significantly reduced at t1 in all groups compared to t0, but recovered up to the third postoperative day (t3). RSO(2) in contrast was significantly reduced in all groups compared to t0 at the third postoperative day (t3). The relative proportion of the intervals compared to the total measurement time for SatO(2) shifted in both anaesthesia procedures: before surgery (N0) the most frequented interval was 96-100%, after surgery (N1, N2) it was 88-91%. There was no correlation between rSO(2), the restitution of the tested cognitive functions and SatO(2).

CONCLUSIONS

Cognitive functions recovered completely during the first 3 postoperative days in patients scheduled for elective hip surgery under general or regional anaesthesia regardless of age and type of anaesthesia. This restitution of cognition occurred despite a significant decrease of cerebral oxygenation (rSO(2)) and despite an increase of nocturnal hypoxaemic intervals. Changes of the rsO(2) up to 3% below the baseline values (measured by NIRS) do not predict cognitive restitution. A minimal limiting value of the rSO(2) could not be defined.